ViewPager第一次工作正常,但再次重新加载,得到错误java.lang.IllegalStateException？

Question

我有一个ViewPager,其中10个图像来自webservices(JSON),起初ViewPager工作顺利(很好).

但当从活动回来并再次重新打开它时, 我收到此错误:

java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! 

Expected adapter item count: 10, found: 0 Pager id: com.akm.demo.activities:id/slideShowPager Pager class: class android.support.v4.view.ViewPager 

在主Activity类中

if (mSlideShowData != null) { // mSlideShowData is An ArrayList of the Images Which I pass to ImagePagerAdapter
adapter = new ImagePagerAdapter(getContext(), mSlideShowData);
slideShowPager.setAdapter(adapter);

//slideShowPager.invalidate();
((PagerAdapter)slideShowPager.getAdapter()).notifyDataSetChanged(); 
}

 else{
Toast toast = Toast.makeText(getContext(), "No Record Found", Toast.LENGTH_LONG);
toast.setGravity(Gravity.CENTER, 0, 0);
    toast.show();

ImagePagerAdapter.java

public class ImagePagerAdapter extends PagerAdapter {

private Context mContext;
private ImageLoader mImageLoader; // It's use for downloading the image from server
private ArrayList<SlideShowData> slideShowImages; // In this I have all the detail of the image from  API

public ImagePagerAdapter(Context context, ArrayList<SlideShowData> mSlideShowData) {
    mContext = context;
    slideShowImages = mSlideShowData;
    mImageLoader = new ImageLoader(mContext);

}

@Override
public int getItemPosition(Object object) {
     return POSITION_NONE;
}

@Override
public int getCount() {
    return slideShowImages.size();
}

@Override
public boolean isViewFromObject(View view, Object object) {
    return view == ((ImageView) object);
}



@Override
public Object instantiateItem(ViewGroup container, int position) {

    ImageView imageViewSlideShow = new ImageView(mContext);
    int padding = mContext.getResources().getDimensionPixelSize(R.dimen.padding_medium);
    imageViewSlideShow.setPadding(padding, padding, padding, padding);
    imageViewSlideShow.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
    mImageLoader.DisplayImage(ServiceURLs.URL+"/photos/"+slideShowImages.get(position).photo_name, R.drawable.loading, imageViewSlideShow);
    ((ViewPager) container).addView(imageViewSlideShow, 0);
    return imageViewSlideShow;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    ((ViewPager) container).removeView((ImageView) object);

}

@Override
public void notifyDataSetChanged() {
        super.notifyDataSetChanged();
}

}

为了解决方案,我试过:

@Override
public int getItemPosition(Object object) {
     return POSITION_NONE;
}

//And

slideShowPager.getAdapter().notifyDataSetChanged();

我从stackoverflow获得的解决方案但无法正常工作.

工作需要改变什么？

解

earlier I am Passing the ArrayList But this time String Array **(working )** Really I don't know whats the problem with the ArrayList

Answer 1

问题的原因可以在某些测量期间刷新寻呼机,在这种情况下将刷新适配器的计数,如果此计数与保存的计数不相等,您将看到错误.所以我的解决方案是:

public abstract class ViewPagerCursorAdapter extends PagerAdapter {

    private int mCount;

    public ViewPagerCursorAdapter(Context ctx, Cursor cursor, int resource) {
        super();
        ...
        mCount = cursor.getCount();
        ...
    }

    @Override
    public int getCount() {
        return mCount;
    }

    public Cursor swapCursor(Cursor newCursor) {
        ...
        mCount = newCursor.getCount();
        notifyDataSetChanged();
    }
}

祝好运.

Answer 2

他们给出的答案适用于我的类似问题。我只是在生产中，不知道所有这些代码是如何工作的，但他们所说的对我在你的另一个线程中有所帮助。您必须像他们所说的那样在您设置或删除图像的地方进行通知。

所以，我认为你的问题是你必须在 onCreateView() 和 destroyItem() 之后发出通知..我会在这里添加已经建议的解决方案..我想应该这样做..希望我是没有误导你..祝你好运..

     slideShowPager.getAdapter().notifyDataSetChanged();

td：lr；最后，你的两个函数 onCreateView() 和 destroyItem() 中的那一行可能会起作用